Treatment of materials containing coal



with water.

EDWIN EDSER, HENRY LIVING-STONE SULMAN, AND FRANK BUTLER JONES OF LONDON, ENGLAND, ASSIGNORS TO MINERALS SEPARATION NORTH AMERI- CAN CORPORATION, OF NEW YORK, Y. r

TREATMENT or MATERIALS CONTAINING COAL.

No Drawing.

T 0 all whom it may concern:

Be it known that we, EDWIN EDSER, residing at 'Brockley, London, England, HENRY LIVINGSTONE SULMAN, and FRANK BUTLER 'Jo'NEs, both residing at London, England, all subjects of the King of England, have invented certain new and useful Improvements in the Treatment of Materials Containing Coal, of which the following is a specification.

This invention consists in improvements in or relating to the treatment of materials containing coal, such as poor coal, dross, coal refuse, or ,washings from coal plant, by a froth-flotation process of concentration, and the present invention relates particularly to the treatment of poor coal con-' i disseminate minute air bubbles throughout taming- (a) good coal, I c (b) ca'rboniferous shale or bone coal, and (c) gangue or earthy matter, such as clay, carbonates, rocky interlaminations and the like.

Broadly speaking, in the application of the froth-flotation process to the recovery of coal from coal-bearing materials, the powdered material, suspended in liquid, is

subjected to agitation and aeration to disseminate minute air bubbles throughout the,

liquid in such a Way that the coal particles are caught in the air-water surface of the bubbles and floated in the form of a froth, and thereby, separated from the material which is not caught by the bubbles.

In the froth-flotation process it is wellknown that there may be added to the liquid a frothing agent, such vas oil.

In the practical application of the frothflotation'process it is also known to add to the liquid a modifying or deflocculating agent which causes the Water effectively to wet the gangue particles and prevents these gangue particles from adhering to the gaseous bubbles.

Many agents which are efl'ective as froth ing agents are soluble in water or miscible On .the other hand, many frothing agents are insoluble or immiscible in water: this is substances. I

We have found that if the frothing agent employed is soluble in water or miscible particularly true of oily Specification of Letters Patent. Patentgd June 6, 1922. Application filed November 12, 1920. Serial No. 423,613),

carbonaceous sh'ale,.or bone coal, can also be floated 'to the. exclusion of the gangue.

According to the present invention, therefore, a process for the differential separation of the constituents of a coal of the type above referred to consists in sub'ecting the powdered material, suspends in liquid, to agitation and aeration first in the presence of a soluble frothing agent so" as to the liquid in such a way that the particles of good coal are floated in the form of a; froth,'after which'a minute quantity of an immiscible or oily agent is added to the pulp, which is again subjected to agitation and aeration'to ensure the flotation of the shale or bone coal.

Among the soluble frothing agents which can beused to ensure the differential flotation of good coal, cresol (cresylic acid) may be mentioned as an example.

The apparatus in which this process is carried out may be any of the known types of apparatus which are at present used in the froth-flotation process of concentrating ores. 1

The following example illustrates the application of this process.

' The material used in this testwas an Indian bituminous coal which contained 16.1 of ash and gave 12000 British thermal units per 'lb. In a'test on this material 1200 grammes were crushed to pass a screen of 20 meshes to the linear inch and were mixed with water to form a 4:1 pulp- The pulp was placed in a laboratory flotation machine of the sub-aeration type. It was agitated and aerated in the usual way. In order to ensure the production of a first concentrate containing pure coal, a soluble frothing agent was added consisting of cresol at the rate of ths lb. per ton of crude material.

The first froth concentrate amounted to In order now' to recover the bone coal or carbonaceous shale there was added to the.

lb. The residue comprising 7% of the orig inal; contained 58% of ash and gave only a trifling calorific value.

In this test the circuit was neutral. Whatwe claim as our invention and desire to secure by Letters Patent is 1. A process of concentrating impure coal N containing good coal, bone. coal, and gangue,

which consists in subjecting the material to froth-flotation separation with a soluble frothing agent to yield a concentrate relatively high in pure coal and subjecting theremaining pulpto further froth flotationwith a frothing agent. which includes an insoluble selecting agent to yield a concentrate relatively high in bone coal.

29 A process of concentrating impure coal containing good coal, bone coal, and

gangu'e, which consists in subjecting the material to froth flotation separation with a soluble frothing agent to yield a concentrate tively high in bone coal 3. A process of concentrating impure coal containing good coal, bone coal, and gangue, which consists in subjecting the material to froth-flotation separation with" cresol to yield a concentrate relatively high in pure coal and subjecting the remainin pulp to further froth-flotation with a frothing agent which includes an insoluble oil to yield a concentrate relatively high hone coal.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses EDWIN EDSER. HENRY LIVINGE ETQNE SULMAN, FRANK BUTLER JGJEIESD Witnesses:

J. Water LILIAN M. HALLAM 

